On Wed, Aug 7, 2019 at 7:48 PM Bruno Marchal <[email protected]> wrote:
> On 7 Aug 2019, at 06:08, Bruce Kellett <[email protected]> wrote: > > > Unitary evolution is an assumption. > > Yes. It is called Quantum Mechanics (without collapse). > No, it is actually just the Schroedinger equation. This works in certain circumstances, but its universal validity has never been tested -- it is just an unproven assumption. It is manifestly violated in essentially every experiment that is > performed. As I said, it serves no useful purpose to maintain that the > superposition persists after a definite result has been obtained. It might > satisfy your existential angst, but it has no role in physics. > > Physics is not metaphysics, especially if we are asked to not try to > figure out what is happening. > We figure out what is happening by forming theories that can be used to predict the future. We eschew metaphysics, which is figuring out the unknowable. > The whole point of Everett is to regain consistency of QM, without > collapse, and it explains well the “illusion” of definite outcomes, which > already does not exist in arithmetic. > Everett has many holes. It does not predict how to calculate probabilities. It does not explain why we get singular outcomes, and it does not even begin to answer the fundamental problem of the preferred basis for observation. > You seem to want to change the theory to save the illusion of definite > outcome. > Definite outcomes are not an illusion -- they are the reality that is observed, which it is the purpose of physics to explain. Not only you need to abandon Mechanism (as you do), but here it looks you > need to abandon QM, or to re-introduce some non unitary evolution in > nature, but we know that this has never work, and it transforms non > locality into action at a distance, also, not quite compatible with > relativity. > There are other possibilities to get from unitary evolution to the observed outcomes. I refer you again to Zurek for some substantial recent advances on these questions. Namely, einselection, envariance, and quantum Darwinism, with the environment as witness. Bruce -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/CAFxXSLTpqcNCXePXriP02haJaFcyHkcEk4Xd4m%2BqvCAbMs_zxA%40mail.gmail.com.
